General Science Mixed Quiz: Set 155

The retina is the innermost coat of the eyeball and it carries the photoreceptor cells, the rods and the cones, which convert light into nerve impulses that the optic nerve carries to the brain; the image formed on the retina is real and inverted, and the brain interprets it as…

Sericulture is the rearing of silkworms for the production of raw silk, and it includes the growing of mulberry, on whose leaves the mulberry silkworm feeds; India produces mulberry silk as well as the wild varieties tasar, eri and muga, the last being special to Assam.

The mud of a tidal swamp is waterlogged and almost free of oxygen, so these plants send up roots that grow vertically out of the soil into the air and take in oxygen through pores; such roots grow against gravity and are therefore called negatively geotropic.

The slightest push makes the ball fall off and it does not come back. A body is in unstable equilibrium when a small displacement lowers its centre of gravity, so the forces acting on it move it further away instead of back.

Only statement II is correct: a small amount of gypsum is added to cement to slow down its setting. Portland cement is made by heating limestone and clay to form clinker, which is then ground with about 2 to 3 per cent gypsum (calcium sulphate dihydrate).

The silkworm's silk gland secretes a protein called fibroin, and over it a second protein, sericin, which acts as a gum and hardens the cocoon; boiling the cocoon softens the sericin so the filament can be reeled, and removing it afterwards is called degumming, which gives silk its lustre and…

Rhodopsin, also called visual purple, is the pigment of the rod cells; it is extremely sensitive to light, which is why rods allow us to see in dim light, though only in shades of black and white.

The restoring force on the bob is mg sin θ. For small angles sin θ is almost equal to θ, so the force becomes proportional to the displacement and points back towards the mean position.

In Opuntia and in many Euphorbia species the leaves are reduced to spines to cut down transpiration, and the stem takes over photosynthesis by becoming flattened, green and fleshy; such a stem is a phylloclade.

A beam seen from the side is visible only because tiny particles send some of its light sideways. Light travelling in a straight line cannot enter our eyes unless something redirects it towards us.

In myopia the eyeball is too long or the lens too strongly curved, so light from a distant object is brought to a focus in front of the retina and the distant object appears blurred.

The stapedius, only about 1 millimetre long, is the smallest skeletal muscle in the human body. It lies in the middle ear and is attached to the stapes, which is itself the smallest bone of the body.

In a monocot leaf, such as that of wheat, maize, grass, banana or canna, the veins run side by side along the length of the lamina without forming a network, and this parallel venation goes with the other monocot features: one cotyledon in the seed, a fibrous root system, scattered…

The torr is a unit of pressure named after Evangelista Torricelli, the Italian scientist who invented the mercury barometer in 1643.

The blind spot, also called the optic disc, is the small area of the retina from which the fibres of the optic nerve pass out of the eyeball; it has neither rods nor cones, so an image falling on it is not registered and we do not notice the gap…

It is called the master gland because its secretions control other glands: thyroid stimulating hormone drives the thyroid, adrenocorticotropic hormone the adrenal cortex, and the gonadotropins the testes and ovaries, besides its own growth hormone.

In a racemose inflorescence the main axis does not end in a flower but keeps growing, so the lowest flower is the oldest and the youngest buds are at the tip; this upward order is called acropetal, as in radish, mustard and Larkspur.

The Eustachian tube, also called the auditory tube, runs from the cavity of the middle ear to the nasopharynx, the upper part of the throat behind the nose, and its function is to keep the air pressure on the inner side of the eardrum equal to the pressure outside.

In vexillary or papilionaceous aestivation the corolla has five petals of unequal size: one large posterior petal, the standard, which covers two lateral wing petals, which in turn cover the two smallest anterior petals that are fused into a keel.

Rhodopsin, the pigment of the rod cells that makes vision in dim light possible, is formed from a derivative of vitamin A, so when the vitamin is lacking the rods cannot work properly and the person is unable to see in faint light, a condition called night blindness or nyctalopia…